Flex-Fuel Sensor Technical Info
New User
Joined: Apr 2009
Posts: 2
Likes: 0
Just writing to let you know that my Flex Fuel sensor is still working, but I believe the stupid 20 pin connector is not making full contact, because the check engine light comes on after heavy rain, or any exposure to a lot of water. Does anyone have the wiring diagram for the flex fuel sensor and the abs that run through the 20 pin connector underneath the drivers seat?
Thanks,
Steve
btw toehead, how's the emulator going?
Thanks,
Steve
btw toehead, how's the emulator going?
New User
Joined: Jan 2011
Posts: 3
Likes: 0
flex fuel sensor
Hubby just recently purchased a 2000 Ford Ranger XLT with a bad flex fuel sensor. I found this forum and printed it up for him, but he would like to know if anyone knows what the normal output of the original flex fuel sensor is? Also, what would the output look like if scoped? Thanks
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5th Wheeling
Joined: Aug 2008
Posts: 43
Likes: 2
Hello,
The normal output for the sensor is a 5 volt square wave. The frequency and duty cycle depends on the ethanol concentration and temperature of the fuel. I don't remember the numbers I used (I used for normal gasoline) but I got them from alldata.
The normal output for the sensor is a 5 volt square wave. The frequency and duty cycle depends on the ethanol concentration and temperature of the fuel. I don't remember the numbers I used (I used for normal gasoline) but I got them from alldata.
5th Wheeling
Joined: Aug 2008
Posts: 43
Likes: 2
You need to use a transistor. The diagram that I posted will give you a working circuit for regular gas! Edit, IIRC the ECU is looking for the low side, so I used a transistor driven by a 555 to pull a signal low through a pull-up resistor.
New User
Joined: Dec 2011
Posts: 8
Likes: 0
Hi, looks like this thread has been around the block....LOL.....
I have this problem (PO178) and have checked the wiring and have 12v,5v, and a ground on my trucks wiring going to the Flex Sensor.
I built the emulator as per Toeheads diagram but the truck doesn't like it and I still get the code.
I've checked my circuit board about 100 times trying to see if I made a mistake, I'm using the TLC 555 timer, and 2N3906 PNP transistors, when I test the circuit in multisim (software) it looks like it works but I can't test it on the table or in the truck except to see it doesn't work.
Anybody able to help a guy out?
I have this problem (PO178) and have checked the wiring and have 12v,5v, and a ground on my trucks wiring going to the Flex Sensor.
I built the emulator as per Toeheads diagram but the truck doesn't like it and I still get the code.
I've checked my circuit board about 100 times trying to see if I made a mistake, I'm using the TLC 555 timer, and 2N3906 PNP transistors, when I test the circuit in multisim (software) it looks like it works but I can't test it on the table or in the truck except to see it doesn't work.
Anybody able to help a guy out?